1. Glomerular filtration - Passive, fluid passes from lumen of glomerular capillary into glomerular capsule of renal tubule.
2. Tubular reabsorption - Moves most of the filtrate into the blood, leaving salt water and wastes in the tubule. Some desirable solutes are absorbed and others move passively from the lumen into the interstitial spaces.
3. Tubular secretion - Essentially the reverse of tubular reabsorption. Process by which the kidneys can rid the blood of additional unwanted substances (creatine, ammonia)